External health checking of virtual private cloud network environments

ABSTRACT

Systems and methods are described to enable health checking of computing devices within a virtual private cloud (VPC) networking environment, without requiring that the devices be accessible via a public network address. An endpoint is placed within the VPC, which enables interaction with an external health checking system via a substrate network. The endpoint handles communications between the heath checking system and the VPC, and can modify data originating from the health checking system such that it appears to originate from the endpoint. From the viewpoint of the VPC, the endpoint itself may appear to be conducting health checking. Thus, external health checking can be used on a VPC without compromising the security of the VPC by requiring that a portion of the VPC be externally addressable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 15/245,089, now issued as U.S. Pat. No. 9,992,086, entitled EXTERNAL HEALTH CHECKING OF VIRTUAL PRIVATE CLOUD NETWORK ENVIRONMENTS and filed Aug. 23, 2016, the entirety of which is incorporated herein by reference.

BACKGROUND

Generally described, computing devices utilize a communication network, or a series of communication networks, to exchange data. Companies and organizations operate computer networks that interconnect a number of computing devices to support operations or provide services to third parties. The computing systems can be located in a single geographic location or located in multiple, distinct geographic locations (e.g., interconnected via private or public communication networks). Specifically, data centers or data processing centers, herein generally referred to as “data centers,” may include a number of interconnected computing systems to provide computing resources to users of the data center. The data centers may be private data centers operated on behalf of an organization or public data centers operated on behalf, or for the benefit of, the general public.

To facilitate increased utilization of data center resources, virtualization technologies may allow a single physical computing device to host one or more instances of virtual machines that appear and operate as independent computing devices to users of a data center. With virtualization, the single physical computing device can create, maintain, delete or otherwise manage virtual machines in a dynamic matter. In turn, users can request computer resources from a data center, including single computing devices or a configuration of networked computing devices, and be provided with varying numbers of virtual machine resources.

Generally, physical networks include a number of hardware devices that receive packets from a source network component and forward the packets to designated recipient network components. In physical networks, packet routing hardware devices are typically referred to as routers, which are implemented on stand-alone computing devices connected to a physical network. With the advent of virtualization technologies, networks and routing for those networks can now be simulated using commodity computing devices rather than actual routers.

Virtualized networks provide advantages over traditional networks, in that the can be rapidly created, configured, or destroyed without reconfiguring underlying physical hardware devices. However, they can also add a layer of complexity over traditional systems. For example, virtualized systems may not have direct physical addresses, as traditional systems would, making transmission of communications between virtualized systems more difficult. Moreover, at least some virtualized systems may be configured to be private, such that public network addressing schemes, which otherwise serve to enable communications between virtualized systems, are not directly usable to communicate between virtualized systems. Thus, existing functionalities and practices may not be directly usable on virtualized systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an embodiment of a substrate network having computing nodes associated with a virtual computer network;

FIG. 2 is a block diagram of the substrate network of FIG. 1 illustrating logical networking functionality;

FIG. 3 is a block diagram of logical view of the substrate network of FIG. 1 illustrating hosted virtual private cloud networks, as well as a health check system and an intercloud communication manager enabling communications between elements of the substrate network;

FIG. 4 is a block diagram depicting an illustrative configuration of one embodiment of a server than may implement a health check endpoint within a virtual private cloud network;

FIGS. 5A and 5B are block diagrams depicting illustrative interactions of the health check system and virtual private cloud networks to provide health checks within the virtual private cloud networks via a health check endpoint; and

FIG. 6 is a flow chart depicting an illustrative routine for providing health checks within a virtual private cloud network using a health check endpoint.

DETAILED DESCRIPTION

Generally described, the present disclosure relates to providing externally originating health checking functionality in a virtual private cloud network environment, without requiring the virtual private cloud network environment to be publically or externally addressable. Moreover, aspects of the present disclosure relate to utilizing such health checking functionality to enable failover mechanisms within the virtual private cloud network environment, such as the use of failover DNS records to route traffic away from failed servers within the virtual private cloud network environment. The term “virtual private cloud network environment” (sometimes shortened to “virtual private cloud” or simply “VPC”) generally refers to a virtualized network environment, in which a collection of computing devices is enabled by a substrate network to communicate, including for example as if the collection of computing devices existed within a local area network (LAN) environment. Accordingly, the devices within a VPC may often share a common subnet, and (from the perspective of the devices) directly communicate with one another without the use of complex routing protocols. However, unlike traditional LANs, the devices within a VPC need not share a direct physical interconnection. Instead, the devices may be located in geographically diverse regions, and in some instances may themselves be virtual devices (e.g., virtual machines). A substrate (e.g., physical) network, as will be described below, may encapsulate or otherwise alter communications from devices associated with the VPC to create the illusion, from the point of view of devices within the VPC, that a LAN environment exists. VPCs provide many advantages over traditional LANs, in that the configuration of computing devices can be changed dynamically, via software, without changing a physical configuration of devices. Moreover, VPCs maintain many benefits of traditional LANs, in that communications between the computing devices are relatively simple and secure. However, like traditional LANs, communications into a VPC from an external source (e.g., a publically addressed server) generally required the VPC to be at least in part publically addressable, and to have a computing device open to communications from a public space. This situation can be disadvantageous, in that it can reduce the security of the VPC. One solution to this issue is to implement all required services within the VPC itself. However, this solution can require high levels of configuration by a VPC owner, and decreases efficiency by requiring that common functionalities be duplicated between VPCs. For example, one functionality that may be beneficial within VPCs is the conducting of “health checks,” whereby a first server transmits pre-defined data to a second server and waits for a designated response, in order to verify that the second server is operating correctly. In the instance that the server is not operating correctly, compensating action can be taken, such as rebooting the second server or rerouting requests away from the second server. While each VPC may include its own independent health checking server, this leads to high inefficiencies and duplication. Conversely, utilization of an external health checking server exposes the VPC to public addressing, thereby decreasing security.

To address these issues, the present disclosure enables the creation of a health checking endpoint within a VPC, which provides “local” health checking services within the VPC in a manner that appears to steam from the health checking endpoint itself. Thus, the use of a health checking endpoint does not require public exposure of the VPC, and maintains its security. However, the health checking endpoint disclosed herein is not required to generate health checking data itself, but can instead retrieve the data from an external health checking service via the substrate network. Thus, the health checking endpoint can be implemented with limited computing resources within the VPC, and the health checking functionality provided by the health checking service can be shared (e.g., invisibly) among multiple VPCs. The overall computing resources of the system are therefore reduced, and the efficiency increased, when compared within independent implementation of health checking systems within distinct VPCs. As disclosed herein, the substrate network may provide an intercloud communication manager to correctly route communications between the health checking system and individual VPCs, thus enabling the health checking system to communicate with multiple VPCs without knowledge of either the VPCs underlying substrate network addresses or knowledge of the VPCs internal, virtualized network addresses. Accordingly, by operating “below” the virtualization layer of a virtual private cloud or other virtualized network, the embodiments described herein can provide the illusion of local services within a VPC while maintaining security within the VPC and increasing efficiency over independently-implemented services.

As will be appreciated by one of skill in the art in light of the present disclosure, the embodiments disclosed herein improves the ability of computing systems, such as those implementing virtual private cloud network environments, to utilize external services without comprising security of the computing devices or requiring the computing devices to be externally addressable via a virtual network. Specifically, aspects of the present disclosure enable endpoints within virtual networks, such as a VPC, that appear to directly provide services (such as health checking services) directly within the virtual network, but which in fact provide such services via communications with external devices over the substrate network, thus providing both the efficiency of centralized systems and the security of localized systems. Moreover, the presently disclosed embodiments address technical problems inherent within computing systems; specifically, the inability of computing devices to interact with external services via a communication network without at least partly compromising security, as well as the inability of computing devices to locally replicate systems with the same efficiency as a centralized system. These technical problems are addressed by the various technical solutions described herein, including the use of endpoints within a VPC that provide the appearance of locally-originating services while utilizing external services. Thus, the present disclosure represents an improvement on existing virtual network systems and computing systems in general.

The following section discusses various embodiments of managed networks for network data transmission analysis. Following that is further discussion of systems and methods enabling source-dependent address resolution.

Managed Computer Networks for Network Data Transmission Analysis

With the advent of virtualization technologies, networks and routing for those networks can now be simulated using commodity hardware components. For example, virtualization technologies can be adapted to allow a single physical computing machine to be shared among multiple virtual networks by hosting one or more virtual machines on the single physical computing machine. Each such virtual machine can be a software simulation acting as a distinct logical computing system that provides users with the illusion that they are the sole operators and administrators of a given hardware computing resource. In addition, as routing can be accomplished through software, additional routing flexibility can be provided to the virtual network in comparison with traditional routing. As a result, in some implementations, supplemental information other than packet information can be used to determine network routing.

Aspects of the present disclosure will be described with regard to illustrative logical networking functionality for managed computer networks, such as for virtual computer networks that are provided on behalf of users or other entities. In at least some embodiments, the techniques enable a user to configure or specify a network topology, routing costs, routing paths and/or other information for a virtual or overlay computer network including logical networking devices that are each associated with a specified group of multiple physical computing nodes. For example, a user (e.g., a network administrator for an organization) or service provider may configure a virtual or overlay network based on detected events, processing criteria, or upon request. With the network configuration specified for a virtual computer network, the functionally and operation of the virtual network can be simulated on physical computing nodes operating virtualization technologies. In some embodiments, multiple users or entities (e.g. businesses or other organizations) can access the system as tenants of the system, each having their own virtual network in the system. In one embodiment, a user's access and/or network traffic is transparent to other users. For example, even though physical components of a network may be shared, a user of a virtual network may not see another user's network traffic on another virtual network if monitoring traffic on the virtual network.

By way of overview, FIGS. 1 and 2 discuss embodiments where communications between multiple computing nodes of the virtual computer network emulate functionality that would be provided by logical networking devices if they were physically present. In some embodiments, some or all of the emulation are performed by an overlay network manager system. One skilled in the relevant art will appreciate, however, that the disclosed virtual computer network is illustrative in nature and should not be construed as limiting.

Overlay Network Manager

FIG. 1 is a network diagram illustrating an embodiment of an overlay network manager system (ONM) for managing computing nodes associated with a virtual computer network. Virtual network communications can be overlaid on one or more intermediate physical networks in a manner transparent to the computing nodes. In this example, the ONM system includes a system manager module 110 and multiple communication manager modules 109 a, 109 b, 109 c, 109 d, 150 to facilitate the configuring and managing communications on the virtual computer network.

The illustrated example includes an example data center 100 with multiple physical computing systems operated on behalf of the ONM system. The example data center 100 is connected to a global internet 135 external to the data center 100. The global internet can provide access to one or more computing systems 145 a via private network 140, to one or more other globally accessible data centers 160 that each have multiple computing systems, and to one or more other computing systems 145 b. The global internet 135 can be a publicly accessible network of networks, such as the Internet, and the private network 140 can be an organization's network that is wholly or partially inaccessible from computing systems external to the private network 140. Computing systems 145 b can be home computing systems or mobile computing devices that each connects directly to the global internet 135 (e.g., via a telephone line, cable modem, a Digital Subscriber Line (“DSL”), cellular network or other wireless connection, etc.).

The example data center 100 includes a number of physical computing systems 105 a-105 d and a Communication Manager module 150 that executes on one or more other computing systems. The example data center further includes a System Manager module 110 that executes on one or more computing systems. In this example, each physical computing system 105 a-105 d hosts multiple virtual machine computing nodes and includes an associated virtual machine (“VM”) communication manager module (e.g., as part of a virtual machine hypervisor monitor for the physical computing system). Such VM communications manager modules and VM computing nodes include VM Communication Manager module 109 a and virtual machines 107 a on host computing system 105 a, and VM Communication Manager module 109 d and virtual machines 107 d on host computing system 105 d.

This illustrative data center 100 further includes multiple physical networking devices, such as switches 115 a-115 b, edge router devices 125 a-125 c, and core router devices 130 a-130 c. Switch 115 a is part of a physical sub-network that includes physical computing systems 105 a-105 c, and is connected to edge router 125 a. Switch 115 b is part of a distinct physical sub-network that includes the System Manager module 110, and is connected to edge router 125 b. The physical sub-networks established by switches 115 a-115 b, in turn, are connected to each other and other networks (e.g., the global internet 135) via an intermediate communication network 120, which includes the edge routers 125 a-125 c and the core routers 130 a-130 c. The edge routers 125 a-125 c provide gateways between two or more sub-networks or networks. For example, edge router 125 a provides a gateway between the physical sub-network established by switch 115 a and the interconnection network 120, while edge router 125 c provides a gateway between the interconnection network 120 and global internet 135. The core routers 130 a-130 c manage communications within the interconnection network 120, such as by routing or otherwise forwarding packets or other data transmissions as appropriate based on characteristics of such data transmissions (e.g., header information including source and/or destination addresses, protocol identifiers, etc.) and/or the characteristics of the interconnection network 120 itself (e.g., routes based on the physical network topology, etc.).

The System Manager module 110 and Communication Manager module 109 can configure, authorize, and otherwise manage communications between associated computing nodes, including providing logical networking functionality for one or more virtual computer networks that are provided using the computing nodes. For example, Communication Manager module 109 a and 109 c manages associated virtual machine computing nodes 107 a and 107 c and each of the other Communication Manager modules can similarly manage communications for a group of one or more other associated computing nodes. The Communication Manager modules can configure communications between computing nodes so as to overlay a virtual network over one or more intermediate physical networks that are used as a substrate network, such as over the interconnection network 120.

Furthermore, a particular virtual network can optionally be extended beyond the data center 100, such as to one or more other data centers 160 which can be at geographical locations distinct from the first data center 100. Such data centers or other geographical locations of computing nodes can be inter-connected in various manners, including via one or more public networks, via a private connection such as a direct or VPN connection, or the like. In addition, such data centers can each include one or more other Communication Manager modules that manage communications for computing systems at that data. In some embodiments, a central Communication Manager module can coordinate and manage communications among multiple data centers.

Thus, as one illustrative example, one of the virtual machine computing nodes 107 a 1 on computing system 105 a can be part of the same virtual local computer network as one of the virtual machine computing nodes 107 d 1 on computing system 105 d. The virtual machine 107 a 1 can then direct an outgoing communication to the destination virtual machine computing node 107 d 1, such as by specifying a virtual network address for that destination virtual machine computing node. The Communication Manager module 109 a receives the outgoing communication, and in at least some embodiments determines whether to authorize the sending of the outgoing communication. By filtering unauthorized communications to computing nodes, network isolation and security of entities' virtual computer networks can be enhanced.

The Communication Manager module 109 a can determine the actual physical network location corresponding to the destination virtual network address for the communication. For example, the Communication Manager module 109 a can determine the actual destination network address by dynamically interacting with the System Manager module 110, or can have previously determined and stored that information. The Communication Manager module 109 a then re-headers or otherwise modifies the outgoing communication so that it is directed to Communication Manager module 109 d using an actual substrate network address.

When Communication Manager module 109 d receives the communication via the interconnection network 120, it obtains the virtual destination network address for the communication (e.g., by extracting the virtual destination network address from the communication), and determines to which virtual machine computing nodes 107 d the communication is directed. The Communication Manager module 109 d then re-headers or otherwise modifies the incoming communication so that it is directed to the destination virtual machine computing node 107 d 1 using an appropriate virtual network address for the virtual computer network, such as by using the sending virtual machine computing node 107 al's virtual network address as the source network address and by using the destination virtual machine computing node 107 d 1's virtual network address as the destination network address. The Communication Manager module 109 d then forwards the modified communication to the destination virtual machine computing node 107 d 1. In at least some embodiments, before forwarding the incoming communication to the destination virtual machine, the Communication Manager module 109 d can also perform additional steps related to security.

Further, the Communication Manager modules 109 a and/or 109 c on the host computing systems 105 a and 105 c can perform additional actions that correspond to one or more logical specified router devices lying between computing nodes 107 a 1 and 107 c 1 in the virtual network topology. For example, the source computing node 107 a 1 can direct a packet to a logical router local to computing node 107 a 1 (e.g., by including a virtual hardware address for the logical router in the packet header), with that first logical router being expected to forward the packet to the destination node 107 c 1 via the specified logical network topology. The source Communication Manager module 109 a receives or intercepts the packet for the logical first router device and can emulate functionality of some or all of the logical router devices in the network topology, such as by modifying a TTL (“time to live”) hop value for the communication, modifying a virtual destination hardware address, and/or otherwise modify the communication header. Alternatively, some or all the emulation functionality can be performed by the destination Communication Manager module 109 c after it receives the packet.

By providing logical networking functionality, the ONM system provides various benefits. For example, because the various Communication Manager modules manage the overlay virtual network and can emulate the functionality of logical networking devices, in certain embodiments specified networking devices do not need to be physically implemented to provide virtual computer networks, allowing greater flexibility in the design of virtual user networks. Additionally, corresponding modifications to the interconnection network 120 or switches 115 a-115 b are generally not needed to support particular configured network topologies. Nonetheless, a particular network topology for the virtual computer network can be transparently provided to the computing nodes and software programs of a virtual computer network.

Logical/Virtual Networking

FIG. 2 illustrates a more detailed implementation of the ONM system of FIG. 1 supporting logical networking functionality. The ONM system includes more detailed embodiments of the ONM System Manager and ONM Communication Manager of FIG. 1. In FIG. 2, computing node A is sending a communication to computing node H, and the actions of the physically implemented modules 210 and 260 and devices of network 250 in actually sending the communication are shown, as well as emulated actions of the logical router devices 270 a and 270 b in logically sending the communication.

In this example, computing nodes A 205 a and H 255 b are part of a single virtual computer network for entity Z. However, computing nodes can be configured to be part of two distinct sub-networks of the virtual computer network and the logical router devices 270 a and 270 b separate the computing nodes A and H in the virtual network topology. For example, logical router device J 270 a can be a local router device to computing node A and logical router device L 270 b can be a local router device to computing node H.

In FIG. 2, computing nodes A 205 a and H 255 b includes hardware addresses associated with those computing nodes for the virtual computer network, such as virtual hardware addresses that are assigned to the computing nodes by the System Manager module 290 and/or the Communication Manager modules R 210 and S 260. In this example, computing node A has been assigned hardware address “00-05-02-0B-27-44,” and computing node H has been assigned hardware address “00-00-7D-A2-34-11.” In addition, the logical router devices J and L have also each been assigned hardware addresses, which in this example are “00-01-42-09-88-73” and “00-01-42-CD-11-01,” respectively, as well as virtual network addresses, which in this example are “10.0.0.1” and “10.1.5.1,” respectively. The System Manager module 290 maintains provisioning information 292 that identifies where each computing node is actually located and to which entity and/or virtual computer network the computing node belongs.

This example, computing node A 205 a first sends an address resolution protocol (ARP) message request 222-a for virtual hardware address information, where the message is expected to first pass through a logical device J before being forwarded to computing node H. Accordingly, the ARP message request 222-a includes the virtual network address for logical router J (e.g., “10.0.0.1”) and requests the corresponding hardware address for logical router J.

Communication Manager module R intercepts the ARP request 222-a, and obtains a hardware address to provide to computing node A as part of spoofed ARP response message 222-b. The Communication Manager module R can determine the hardware address by, for example, looking up various hardware address information in stored mapping information 212, which can cache information about previously received communications. Communication Manager module R can communicate 227 with the System Manager module 290 to translate the virtual network address for logical router J.

The System Manager module 290 can maintain information 294 related to the topology and/or components of virtual computer networks and provide that information to Communication Manager modules. The Communication Manager module R can then store the received information as part of mapping information 212 for future use. Communication Manager module R then provides computing node A with the hardware address corresponding to logical router J as part of response message 222-b. While request 222-a and response message 222-b actually physically pass between computing node A and Communication Manager module R, from the standpoint of computing node A, its interactions occur with local router device J.

After receiving the response message 222-b, computing node A 205 a creates and initiates the sending of a communication 222-c to computing node H 255 b. From the standpoint of computing node A, the sent communication will be handled as if logical router J 270 a were physically implemented. For example, logical router J could modify the header of the communication 265 a and forward the modified communication 265 b to logical router L 270 a, which would similarly modify the header of the communication 265 b and forward the modified communication 265 c to computing node H. However, communication 222-c is actually intercepted and handled by Communication Manager module R, which modifies the communication as appropriate, and forwards the modified communication over the interconnection network 250 to computing node H by communication 232-3. Communication Manager module R and/or Communication Manager module S may take further actions in this example to modify the communication from computing node A to computing node H or vice versa to provide logical networking functionality. For example, Communication Manager module S can provide computing node H with the hardware address corresponding to logical router L as part of response message 247-e by looking up the hardware address in stored mapping information 262. In one embodiment, a communication manager or computing node encapsulates a packet with another header or label where the additional header specifies the route of the packet. Recipients of the packet can then read the additional header and direct the packet accordingly. A communication manager at the end of the route can remove the additional header.

A user or operator can specify various configuration information for a virtual computer network, such as various network topology information and routing costs associated with the virtual 270 a, 270 b and/or substrate network 250. In turn, the ONM System Manager 290 can select various computing nodes for the virtual computer network. In some embodiments, the selection of a computing node can be based at least in part on a geographical and/or network location of the computing node, such as an absolute location or a relative location to a resource (e.g., other computing nodes of the same virtual network, storage resources to be used by the computing node, etc.). In addition, factors used when selecting a computing node can include: constraints related to capabilities of a computing node, such as resource-related criteria (e.g., an amount of memory, an amount of processor usage, an amount of network bandwidth, and/or an amount of disk space), and/or specialized capabilities available only on a subset of available computing nodes; constraints related to costs, such as based on fees or operating costs associated with use of particular computing nodes; or the like.

Further details regarding operation of a substrate network, such as the implementation of route selection on a substrate networks and virtualized networks are discussed in more detail in U.S. Pat. No. 9,183,028, issued Nov. 10, 2015, entitled “MANAGING VIRTUAL COMPUTING NODES,” (the “'028 patent”), the entirety of which is incorporated by reference herein.

Virtual Private Cloud Service Endpoints

With reference to FIGS. 3-6, aspects of the present disclosure will be described that enable collections of computing devices sharing a virtual private cloud networking environment (e.g., a LAN virtualized within the substrate network described above) to utilize external services via an endpoint within virtual private cloud, which creates the illusion that such services exist within the virtual private cloud itself. Thus, as described below, devices within the virtual private cloud can gain access and use of such external services without any element of the virtual private cloud being publically addressable.

Specifically, with reference to FIG. 3, a block diagram showing a simplified logical environment 800 created by the substrate network 100 of FIG. 1 will be described. As shown in FIG. 3, the logical environment 800 includes one or more virtual private clouds 800 (VPCs), which represent private virtualized networks implemented by a substrate network. Each VPC includes, for example, one or more servers 814, a private domain name system (DNS) server 812, and a health check endpoint 816. The servers 814 may generally provide any network-accessible functionality, such as web page hosting or database hosting, among many others known in the art. The private DNS server 812 may provide DNS functionality to the servers 814 within a VPC 810. Systems and methods for implementing private DNS servers 812 are described in more detail in U.S. patent application Ser. No. 14/750,698, entitled “SELECTIVE ROUTING OF DOMAIN NAME SYSTEM (DNS) REQUESTS” and filed Jun. 25, 2016 (hereinafter, the “'698 application”), which is hereby incorporated by reference. The private DNS server 812 and the servers 814 may be implemented, for example, as virtual machines hosted by physical computing devices of a substrate network. While shown as included within a VPC 810, private DNS servers 812 may in some instances be logically separate from a VPC 810 to which they provide DNS functionality. For example, one or more distinct VPCs 810 may be created to contain a set of private DNS servers 812, each of which is associated with and provides DNS services to one or more customer VPCs 810. Separation of private DNS servers 812 from a serviced VPC 810 may, for example, enable permissions or communications channels of the private DNS server 812 to be modified without altering or compromising security of a customer's VPC 810. Thus, the arrangement of elements within the VPCs 810 is intended to be illustrative.

In accordance with embodiments of the present disclosure, each VPC can further include health check endpoint 816, which may also be implemented as a virtual device by physical computing devices of the substrate network. As described in more detail below, the health check endpoint 816 can function to provide health checking services to the servers 814, to verify that the servers 814 are functioning correctly. For example, the health check endpoint 816 can transmit specially formatted network packets to a server 814 and await a designated response. In the instance that an invalid response is received (e.g., no response, a response without the expected information, a response indicating an error, a substantially delayed response, etc.), the health check endpoint 816 can interact with other elements of the VPC or substrate network in order to take corrective action, such as rebooting the server 814 or removing an address of the server 814 from records of the private DNS server 812. In some instances, a health check endpoint 816 may be implemented as a virtual network interface to a server 814, such that data transmitted to the health check endpoint 816 is effectively transmitted to the server 814 via the virtual network interface. In this context, a health check endpoint 816 may be described as an “elastic network interface” for the server (where elastic designates, for example, that the network interface can be modified dynamically as required by the VPC 810). In some instances, implementation of a health check endpoint 816 as a virtual network interface for a server 814 may eliminate the need for a separate virtual device to implement the health check endpoint 816.

From the point of view of the servers 814 or other components within the VPCs 810, the health checking data received from the health check endpoint 816 can appear to originate at the health check endpoint 816 and thus, to originate within the VPC 810 itself. However, rather than originating health checking data, the health check endpoint 816 can function as an endpoint for data obtained from an external system, depicted as health check system 830. As shown in FIG. 3, the health check system 830 can include a health check manager 832, one or more health check servers 834, and a configuration data store 836. Each component of the health check system 830 may correspond to a physical computing device, or may be implemented as a virtual device by the substrate network. In some instances, the health check system 830 may be implemented as or within a VPC 810. Within the health check system 830, the health check servers 834 can function to generate health check data (e.g., packets formatted to elicit an expected response from a health check target, such as Internet Control Message Protocol [ICMP] echo packets, hypertext transport protocol [HTTP] request packets, etc.) and transmit that health check data to a destination server 814 via a health check endpoint 816.

The health check manager 832 may function to obtain data regarding responses to the health check data, and to determine whether responses from any server 814 indicate that the server 814 has failed. Illustratively, the health check manager 832 may implement criteria, designated by an administrator of a substrate network and/or by an account holder associated with a VPC 810, that designates a server 814 as failed when invalid responses are obtained for at least 85% of health check data transmitted over a threshold (e.g., 5 minute) period.

The information utilized by the health check system 830 can be stored within a configuration data store 836. For example, the health check data store 830 may include information specifying address information for a server 814 (e.g., via universal resource indicator [URI], internet protocol [IP] address, etc.), as well as information specifying what type of health check data should be transmitted to the server, criteria for distinguishing valid or invalid responses, and criteria for determining whether a server has failed based on whether responses are valid or invalid. The configuration data store 836 may correspond to any persistent or substantially persistent data storage, such as a hard drive (HDD), a solid state drive (SDD), network attached storage (NAS), a tape drive, or any combination thereof. The configuration data store 836 may be implemented directly by a physical storage device, or may be implemented by a virtualized storage device that is in turn implemented on an underlying physical storage device.

The various components of the health check system 830 may communicate over a network (not shown in FIG. 3), such as the substrate network of FIG. 1, or a virtual network implemented by the substrate network. In one embodiment, the components of the health check system 830 operate within a VPC distinct from the VPCs 810.

The VPCs 810 and health check system 830 can communicate over a network 840, which may represent a simplified logical view of the substrate network of FIG. 1, or may represent a virtual network implemented by the substrate network. However, because the components of the VPCs 810 can be implemented virtually, their underlying location and network addresses may vary. Moreover, their logical, virtual locations or network addresses may be viewable only within the VPC 810, to ensure the security of the VPC. For example, a server 814 may be assigned the IP address of “10.0.0.1” within a VPC 810, but may have no publically routable IP address. Similarly, the server 814 may be discoverable by use of the private DNS server 812 and the URI “www.server.tld,” but the private DNS server 812 may function only to serve requests for that URI only from sources originating within the VPC 810 (and may or may not have any publically routable address). Accordingly, it may be impossible for the health check system 830 to directly communicate with the health check endpoints 816 within the VPCs 810.

The logical environment 800 therefore further includes an intercloud communication manager 820 enabling communication between the health check system 830 and health check endpoints 816 in VPCs 810. Specifically, the intercloud communication manager 820 can be configured to obtain health check data addressed to an identifier of a VPC (e.g., VPC “A”, VPC “B”, etc.), and to forward that health check data to a health check endpoint 816. In this manner, the intercloud communication manager 820 can function as a “switchboard” between the health check system 830 and the VPCs. In one embodiment, the intercloud communication manager 820 can obtain health check data from the health check system 830, determine a VPC 810 to which the data is directed, and forward the health check data to an underlying substrate network address associated with the health check endpoint 816. In some instances, the data may be encapsulated or otherwise formatted to enable transmission over the substrate network.

The health check endpoint 816, in turn, can obtain health check data forwarded by the intercloud communication manager 820, and transmit the data to a destination server 814. In one embodiment, the health check endpoint 816 can decapsulate the data and forward the decapsulated data to a destination server 816. In another embodiment, the health check endpoint 816 can use the health check data to generate a new health check request, and transmit the new health check request to the servers 814. On receive a response (or lack therefore), the health check endpoint 816 can return the response (or lack thereof) to the intercloud communication manager 820, which may in turn forward the data to the health check system 830. In this manner, communications may occur between the health check system 830 and the VPC 810 in a manner which appears, to the components of the VPCs 810, to occur entirely within the virtual private cloud 810. Moreover, because the communication utilizes an underlying substrate layer, the configuration of the VPC 810 itself need not be modified, and the VPC 810 need not be publically exposed, maintaining the security of the VPC 810.

FIG. 4 depicts one embodiment of an architecture of a server 900 that may implement a health check endpoint 816 described herein. The general architecture of server 900 depicted in FIG. 4 includes an arrangement of computer hardware and software components that may be used to implement aspects of the present disclosure. As illustrated, the server 900 includes a processing unit 904, a network interface 906, a computer readable medium drive 907, an input/output device interface 920, a display 922, and an input device 924, all of which may communicate with one another by way of a communication bus. The network interface 906 may provide connectivity to one or more networks or computing systems, such as the network 840 of FIG. 3. The processing unit 904 may thus receive information and instructions from other computing systems or services via a network. The processing unit 904 may also communicate to and from memory 910 and further provide output information for an optional display 909 via the input/output device interface 920. The input/output device interface 920 may also accept input from the optional input device 924, such as a keyboard, mouse, digital pen, etc. In some embodiments, the server 900 may include more (or fewer) components than those shown in FIG. 4. For example, some embodiments of the server 900 may omit the display 902 and input device 924, while providing input/output capabilities through one or more alternative communication channel (e.g., via the network interface 906).

The memory 910 may include computer program instructions that the processing unit 904 executes in order to implement one or more embodiments. The memory 910 generally includes RAM, ROM and/or other persistent or non-transitory memory. The memory 910 may store an operating system 914 that provides computer program instructions for use by the processing unit 904 in the general administration and operation of the server 900. The memory 910 may further include computer program instructions and other information for implementing aspects of the present disclosure. For example, in one embodiment, the memory 910 includes user interface software 919 that generates user interfaces (and/or instructions therefor) for display upon a computing device, e.g., via a navigation interface such as a web browser installed on the computing device. In addition, memory 910 may include or communicate with one or more auxiliary data stores, such as data store 902, which may correspond to any persistent or substantially persistent data storage, such as a hard drive (HDD), a solid state drive (SDD), network attached storage (NAS), a tape drive, or any combination thereof.

In addition to the user interface module 919, the memory 910 may include health check endpoint software 916 that may be executed by the processing unit 904. In one embodiment, the health check endpoint software 916 implements various aspects of the present disclosure, e.g., facilitating interaction of a health check system 830 with components of a VPC 810.

With reference to FIGS. 5A and 5B, a set of illustrative interactions for utilizing an external health check system 830 within a VPC 810 without requiring components of the VPC 810 to be publically addressable will be described. The interactions between at (1), where the health check system 830 obtains configuration data for a VPC 810. The configuration data may specify, for example, address information of servers 814 to be health checked (e.g., URIs, IP addresses, etc.), a VPC ID associated with the VPC 810 (which may correspond to any identifier sufficient to distinguish the target VPC 810 from other VPCs 810), the data to be used as a health check (e.g., request type, request content, etc.), the criteria for evaluating valid or invalid responses, and the criteria for determining when invalid responses indicate that a target device is unhealthy.

Thereafter, at (2), the health check system 830 transmits a request to the intercloud communication manager 820 to interact with the target VPC 810. Illustratively, the health check system 830 may transmit the VPC ID to the intercloud communication manager 820. At (3), the intercloud communication manager 820 determines a substrate network address of the health check endpoint 816 within the VPC 810, and returns access information to the health check system 830 to enable interaction with a health check endpoint 816. In one embodiment, the intercloud communication manager 820 can function as a “proxy” for communication between the health check system 830 and the virtual private cloud 810. As such, the intercloud communication manager 820 may return, at (4), a network address associated with the intercloud communication manager 820 to which communications to the health check endpoint 816 can be transmitted. In another embodiment, the intercloud communication manager 820 may enable direct communication between the health check system 830 and the virtual private clouds 810, and thus may return, at (4), a substrate network address of the health check endpoint 816.

At (5), the health check system 830 generates health check data packets for transmission to the VPC 810. Illustratively, the various health check servers 834 may generate, using information from within the configuration data store 836, network requests (e.g., HTTP requests) addressed to servers 814 within the VPC 810. At (6), the health check system 830 transmits the health check packets to the intercloud communication manager 820, which in turn, at (7), transmits the health check packets to the health check endpoint 816. Illustratively, either or both of the health check system 830 and the intercloud communication manager 820 may encapsulate the health check data packets to enable transmission on a substrate network. For example, the health check system 830 may encapsulate data packets with routing information for a substrate network, including a VPC ID of the destination VPC 810. The intercloud communication manager 820 may utilize the VPC ID within the encapsulated packets to forward the packets to the health check endpoint 816.

At (8), the health check endpoint 816 obtains the health check data packets generated by the health check system 830, and decapsulates the health check packets. Illustratively, the health check endpoint 816 may strip routing information for a substrate network, resulting in a packet that is routable within the VPC 810. The health check endpoint 816 may make other modifications to the health check packets, such as by replacing a source address of the packets with an address of the health check endpoint 816 within the VPC 810. Thereafter, the health check endpoint 816 transmits the health check packets to one or more destination servers 814. Accordingly, from the viewpoint of the servers 814, it can appear that the received health check data packets originate from within the VPC 810.

While the above discussion of FIG. 5A describes some communications between health check systems 830 and VPCs 810, other communications are possible and contemplated within the scope of the present disclosure. For example, in some instances, servers 814 subject to health checking may be identified by way of a URI that is resolvable via the private DNS server 812. Accordingly, prior transmitting health check data to the server 814, a network address (e.g., a virtual network address within the VPC 810) may be required to be determined. In one embodiment, the health check system 830 may therefore forward a DNS resolution request for the destination URI to the health check endpoint 816, which may interact with the private DNS server 812, and return a destination IP address to the health check system 830. In other embodiments, DNS resolution may occur solely on the health check endpoint 816, such that the health check endpoint 816 is configured to obtain health check data addressed to URI, to determine an IP corresponding the URI, and to forward the health check data to the IP.

The interactions of FIG. 5A are continued with reference to FIG. 5B, where, at (10), a destination server 814 returns a response to the health check data. The response may include any data responsive to the request, such as HTTP content, an error message, etc. In some instances, no response may be received (e.g., in the instance that the server 814 has become unhealthy). In some embodiments, the health check endpoint 816 may detect such a lack of response, and actively return a notification to the health check system 830 of the lack of response. In other embodiments, the health check endpoint 816 may take no action, and the health check system 830 may be configured to determine that the server 814 returned no response by detecting that no response has been received from the health check endpoint 816.

In the instance that the health check endpoint 816 returns data to the health check system 830 (e.g., the response from the server 814 or data indicating that no response was received), the health check endpoint 816, at (11), encapsulates the response for transmission to the health check system 830 via the substrate network. At (12), the health check endpoint 816 transmits the response to the intercloud communication manager 820, which, at (13), transmits the response to the health check system 130.

For the purposes of the present description, it will be assumed that the responses received from at least one server 814 of the VPC 810 indicate that the server 814 has become unhealthy. Such an instance may occur, for example, when a threshold percentage of health check data transmitted to the server 814 result in an invalid response. These responses may be evaluated, for example, by the health check manager 832 to detect, at (14), that the server 814 has become unhealthy.

On detecting that a server 814 has become unhealthy, the health check system 830 may be configured to undertake corrective or compensating action. For example, the health check system 830 may automatically communicate with an underlying host device to request a reboot of the server 814. As a further example, the health check system 830 may utilize aspects of the present disclosure to communicate with a private DNS server 812 to cause the server 814 to be removed from DNS records of the server 812, such that requests to a given URI are directed to other servers 814 (e.g., other servers 814 implementing the same functionality as a failed server 814). Accordingly, at (15), the health check system 830 transmits a notification of the failed server 814 to the intercloud communication manager 820. The notification may, for example, include an IP address (e.g., within the addressing scheme of the VPC 810), and encapsulated for transmission via the substrate network (e.g., with a VPC ID of the destination VPC 810 including as metadata within the encapsulated content).

At (16), the intercloud communication manager 820 forwards the notification of the unhealthy server to the health check endpoint 816 at (17). The health check endpoint 816, at (17), decapsulates the notification and, at (18), forward the notification to the private DNS server 812. Thus, the private DNS server 812 can be notified that a server 814 has become unhealthy, and take actions (e.g. as a “failover”) to remove networking information of the unhealthy server 814 from its records. Such failover may include, for example, removing a network address of the unhealthy server 814 from its records (e.g., by deleting a DNS ‘A’ record) or otherwise modifying DNS responses associated with the unhealthy server 814 (e.g., by modifying DNS “CNAME,” ALIAS” OR “URL” records associated with the unhealthy server 814). While FIG. 5B depicts illustrative interactions enabling communication with a private DNS server 812 within a VPC 810 (e.g., through a health check endpoint 816), these interactions may vary according to the logical location of the private DNS server 812. For example, as described above, private DNS servers 812 may in some instances be implemented within a distinct VPC 810 than the VPC 810 to which they provide services. In some instances, such private DNS servers 812 may be directly addressable by the health check system 830 and thus, communications between the health check system 830 and the private DNS server 812 may not require use of an intercloud communication manager 820 or a health check endpoint 816. While FIG. 5B depicts notifications for unhealthy servers 814 as being transmitted to a private DNS server 812, notifications may additionally or alternatively be sent to other components or devices, such as load balancing devices or host management devices on the substrate network (e.g., to divert traffic from the unhealthy server 814, to restart the unhealthy server 814, etc.), or to other unassociated devices (e.g., logging device) which may be external to a substrate network.

One of skill in the art will appreciate that the interactions of FIGS. 5A and 5B described above enable the use of an external system (e.g., the health check system 830) to implement functionality, such as health checking and DNS failover, within the VPC 810, without requiring components of the VPC 810 to be publically addressable. While the interactions are described with reference to a single server 814 within a single VPC 810, the same or similar interactions may occur with respect to a plurality of VPCs 810 or servers within VPCs 810, in some instances at least partly concurrently. Accordingly, a single health check system 830 may implement health check or failover functionality within a number of different VPCs 810, providing increased efficiency relative to implementation of distinct health check systems in each VPC 810.

With reference to FIG. 6, one illustrative routine 1100 that may be implemented by an external health check system to interact with a VPC without requiring the VPC to be publically addressable will be described. As shown in FIG. 6, the routine may be carried out by interaction of a health check system outside of a target VPC, an endpoint within the target VPC, and a communication manager logically disposed between the health check system and the endpoint. For the purposes of description, the routine 1100 includes only a single round-trip communication between the health check system and the endpoint. However, the same or a substantially similar routine may be used to enable any communications between the health check system and the VPC, such as transmissions for resolving a URI or other identifier of a target device within the VPC to a network address, or transmission for notifying a private DNS server within the VPC that a server has failed a health check.

The routine 1100 begins at block 1102, where the health check system generates one or more health check packets and transmits the packets to a communication manager. Illustratively, the health check packets may be generated based on criteria provided by an administrator of the VPC. For example, the health check packets may include network requests targeted to a destination device within the VPC and intended to elicit an expected response from that destination device, to verify that the destination device is operating normally. In some instances, these health check packets may be encapsulated by the health check system prior to transmission to the communication manager, to enable the packets to be routed correctly on a substrate network hosting the VPC. For example, the packets could be encapsulated with additional header data and addressed to the communication manager, with an identifier of the VPC listed in metadata of the encapsulated packet.

At block 1104, the communication manager obtains the health check packets, and uses information obtained along with or inside of the packets to determine a substrate network address for an endpoint associated with a target VPC. Illustratively, the communication manager may maintain a mapping of substrate network addresses and associated VPC identifiers, such that an endpoint within a VPC may be quickly identified using a corresponding VPC identifier. The communication manager can then forward the health check packets to the endpoint associated with the VPC.

At block 1106, the endpoint within the VPC obtains the health check packets and, at block 1108, decapsulates the packets for transmission within the VPC. While the term “decapsulation” is used herein to describe the process by which an endpoint modifies data packets received via a substrate network to enable transmission over a VPC, this process may in some instances require a substrate network to re-encapsulate the data packets in accordance with operation of the VPC. For example, an endpoint may strip headers or other information associated with transmission between the communication manager and the endpoint, and subsequently add headers or other information enabling transmission of the data packets within the VPC. Thereafter, the endpoint transmits the modified health check packets to a destination device within the VPC. In some instances, the endpoint may make further modifications to the packets, such as modifying a source identifier to create an illusion, within the VPC, that the health check packets originate at the endpoint. Thus, from the point of view of a destination device or other device within the VPC, it may appear that health checks are originating at the endpoint within the VPC, rather than from an external service.

At block 1110, the endpoint obtains a result of transmitting the health check packets to a destination device, which may include, by way of non-limiting example, an expected response (thus indicating that the target device is healthy), an unexpected response, a delayed response, or a lack of response. In the instance that no response is received, the endpoint may generate responsive information for transmission to the health checking system, indicating that no response was received from the destination device. Alternatively, the endpoint may generate no responsive information, and the health checking system may determine that no response was received based on a lack of communications with the endpoint.

At block 1112, the communication manager obtains responsive information (if any) from the endpoint, and forwards the information to the health check system. In one embodiment, the endpoint may encapsulate packets for transmission to the health check system by use of a VPC ID or other identifier associated with the health check system. Thus, the communication manager may determine a substrate network address associated with the health check system, and forward the responsive information to that network address.

At block 1114, the health check system obtains and processes the results of the health check data packets. Illustratively, where health check data packets were sent from a number of different health checking devices, one or more devices, such as a health check manager, may aggregate health check responses to determine whether a destination device within the VPC is considered unhealthy. If no device is considered unhealthy, the health check system may continue normal operation, such as by implementing the routine 1100 at intervals (e.g., every 30 seconds, 1 minute, 10 minutes, etc.). If a device is considered unhealthy, the health check system may take corrective or compensatory action (e.g., as defined by an administrator of the VPC), such as notifying a host device on the substrate network to restart the destination device, or notifying a private DNS server within the VPC to remove a network identifier of the unhealthy device from its DNS records. The routine 1100 then ends at block 1116.

All of the methods and processes described above may be embodied in, and fully automated via, software code modules executed by one or more computers or processors. The code modules may be stored in any type of non-transitory computer-readable medium or other computer storage device. Some or all of the methods may alternatively be embodied in specialized computer hardware.

Conditional language such as, among others, “can,” “could,” “might” or “may,” unless specifically stated otherwise, are otherwise understood within the context as used in general to present that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment.

Disjunctive language such as the phrase “at least one of X, Y or Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., may be either X, Y or Z, or any combination thereof (e.g., X, Y and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain embodiments require at least one of X, at least one of Y or at least one of Z to each be present.

Unless otherwise explicitly stated, articles such as ‘a’ or ‘an’ should generally be interpreted to include one or more described items. Accordingly, phrases such as “a device configured to” are intended to include one or more recited devices. Such one or more recited devices can also be collectively configured to carry out the stated recitations. For example, “a processor configured to carry out recitations A, B and C” can include a first processor configured to carry out recitation A working in conjunction with a second processor configured to carry out recitations B and C.

Any routine descriptions, elements or blocks in the flow diagrams described herein and/or depicted in the attached figures should be understood as potentially representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or elements in the routine. Alternate implementations are included within the scope of the embodiments described herein in which elements or functions may be deleted, or executed out of order from that shown or discussed, including substantially synchronously or in reverse order, depending on the functionality involved as would be understood by those skilled in the art.

It should be emphasized that many variations and modifications may be made to the above-described embodiments, the elements of which are to be understood as being among other acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims. 

What is claimed is:
 1. A system comprising: one or more computing devices external to a virtual private cloud network environment (VPC), the VPC including a target computing device and an endpoint arranged within a virtualized local area network generated by a substrate network hosting the VPC, wherein the one or more computing devices external to the VPC are configured with computer-executable instructions to: generate health check data to transmit to a target computing device within the VPC; and transmit the health check data on the substrate network to the endpoint of the VPC; and one or more computing devices implementing the endpoint of the VPC, wherein the one or more computing devices implementing the endpoint of the VPC are configured with computer-executable instructions to: modify the health check data to designate the endpoint as a source of the health check data; transmit the health check data to the target computing device within the VPC; obtain information responsive to transmission of the health check data; and transmit the information responsive to the health check data to the one or more computing devices external to the VPC.
 2. The system of claim 1, wherein the VPC is configured to deny requests to communicate with the target computing device that originate external to the VPC.
 3. The system of claim 1, wherein the information responsive to the health check data is at least one of a response from the target computing device or an indication that no response has been received from the target virtual computing device.
 4. The system of claim 1, wherein the health check data is transmitted on the substrate network to the endpoint of the VPC by addressing the health check data to a network address of the one or more computing device implementing the endpoint on the substrate network, and wherein the health check data is transmitted to the target computing device within the VPC by addressing the target computing device using a private network address of the VPC.
 5. The system of claim 1, wherein the one or more computing devices external to the VPC are further configured with computer-executable instructions to: determine, based at least in part on the information responsive to the health check data, that the target computing device is unhealthy; and transmit to the endpoint a notification to a domain name system (DNS) server associated with the VPC that the target computing device is unhealthy; and wherein the one or more computing device implementing the endpoint of the VPC are further configured with computer-executable instructions to: obtain the notification from the one or more computing devices external to the VPC; transmit the notification to the DNS server.
 6. Non-transitory computer-readable media comprising computer instructions executable on an endpoint computing device within a virtual private cloud network environment (VPC), the VPC including the endpoint and a target computing device arranged within a virtualized local area network that is generated by a substrate network hosting the VPC, wherein the computer instructions, when executed on the endpoint computing device, cause the endpoint to: obtain health check data generated at a health check system external to the VPC and routed to the endpoint computing device via the substrate network; modify the health check data to designate the endpoint computing device as a source of the health check data; transmit, within the VPC, the health check data from the endpoint computing device to the target computing device; obtain information responsive to the health check data; and route the information responsive to the health check data, on the substrate network, from the endpoint to the health check system external to the VPC.
 7. The non-transitory computer-readable media of claim 6, wherein the target virtual computing device is identified by a private domain name within the VPC, and wherein the computer instructions further cause the endpoint to: obtain, from the health check system, a request to resolve the private domain name; transmit the request to a domain name system (DNS) server associated with the VPC; obtain a response to the request, the response indicating a network address of the target virtual computing device; and return the network address to the health check system.
 8. The non-transitory computer-readable media of claim 6, wherein the computer instructions further cause the endpoint to: obtain, on the substrate network, a notification from the health check system to a domain name system (DNS) server associated with the VPC that the target computing device is unhealthy; and forward, within the VPC, the notification to the DNS server.
 9. The non-transitory computer-readable media of claim 6, wherein the media further comprises computer instructions executable on the health check system to generate the health check data.
 10. The non-transitory computer-readable media of claim 6, wherein the health check data is formatted according to at least one of the Hypertext Transport Protocol (HTTP) or Internet Control Message Protocol (ICMP).
 11. The non-transitory computer-readable media of claim 6, wherein the computer instructions further cause the endpoint to modify the health check data to designate the endpoint computing device as the source of the health check data at least partly by replacing an address of the health check system within the health check data with an address of the endpoint.
 12. The non-transitory computer-readable media of claim 11, wherein the address of the endpoint is an internal address of the VPC.
 13. A method implemented on an endpoint computing device within a virtual private cloud network environment (VPC), the VPC including the endpoint computing device and a target computing device arranged within a virtualized local area network that is generated by a substrate network hosting the VPC, wherein the method comprises: obtaining health check data generated at a health check system external to the VPC and routed to the endpoint via the substrate network; modifying the health check data to designate the endpoint computing device as a source of the health check data; transmitting, within the VPC, the health check data from the endpoint computing device to the target computing device; obtaining information responsive to the health check data; and routing the information responsive to the health check data, on the substrate network, from the endpoint computing device to the health check system external to the VPC.
 14. The method of claim 13, wherein the target virtual computing device is identified by a private domain name within the VPC, and wherein the method further comprises: obtaining, from the health check system, a request to resolve the private domain name; transmitting the request to a domain name system (DNS) server associated with the VPC; obtaining a response to the request, the response indicating a network address of the target virtual computing device; and returning the network address to the health check system.
 15. The method of claim 13 further comprising: obtaining, on the substrate network, a notification from the health check system to a domain name system (DNS) server associated with the VPC that the target computing device is unhealthy; and forwarding, within the VPC, the notification to the DNS server.
 16. The method of claim 13, wherein modifying the health check data to designate the endpoint computing device as the source of the health check data comprises replacing an address of the health check system within the health check data with an address of the endpoint.
 17. A system comprising: one or more computing devices implementing an endpoint within a virtual private cloud network environment (VPC), the VPC including the endpoint and a target computing device arranged within a virtualized local area network that is generated by a substrate network hosting the VPC, wherein the one or more computing devices are configured with computer-executable instructions to: obtain health check data generated at a health check system external to the VPC and routed to the endpoint via the substrate network; modify the health check data to designate the endpoint as a source of the health check data; transmit, within the VPC, the health check data from the endpoint computing device to the target computing device; obtain a response from the target computing device; and route the response, on the substrate network, from the endpoint to the health check system external to the VPC.
 18. The system of claim 17, wherein the target virtual computing device is identified by a private domain name within the VPC, and wherein the one or more computing devices are further configured with computer-executable instructions to: obtain, from the health check system, a request to resolve the private domain name; transmit the request to a domain name system (DNS) server associated with the VPC; obtain a response to the request, the response indicating a network address of the target virtual computing device; and return the network address to the health check system.
 19. The system of claim 17, wherein the one or more computing devices are further configured with computer-executable instructions to: obtain, on the substrate network, a notification from the health check system to a domain name system (DNS) server associated with the VPC that the target computing device is unhealthy; and forward, within the VPC, the notification to the DNS server.
 20. The system of claim 17 further comprising one or more computing devices implementing the health check system, wherein the one or more computing devices implementing the health check system are configured with computer-executable instructions to: generate the health check data; and transmit the health check data to the endpoint via the substrate network. 